Spring pressured electrical contact means



July 19, 1966 1. MINES ETAL SPRING PRESSURED ELECTRICAL CONTACT MEANS Filed Oct. 2, 1964 INVENTORS.

IRVING MINES a SAMUEL MINES ATTORNEY United States Patent 3,261,956 SPRING PRESSURE!) ELECTRICAL CONTACT MEANS Irving Mines and Samuel Mines, Trenton, NJL, assignors to General Plating Company, Trenton, N.J., a

partnership Filed Oct. 2, 1964, Ser. No. 401,017 9 Claims. (Cl. 200-162) This invention relates to electrical contact means, and it particularly relates to electrical contact means utilizable in electrical switches or the like.

In many industries, as, for example, in the electroplating industry, it is constantly necessary to open and close electrical circuits during the course of the work. Ordinary switch devices, such as the standard knife-blade switches, where the switch blade is movable into and out of position between a pair of spring contacts, whereby it forces itself between the contacts while the contacts are biased toward each other, tend to become ineffective or even inoperative after a certain period of time because the contacts tend to lose their resilient bias under the constant pressure of the switch blade. The same is true of other uses, such as fuse holders, in those situations where it is necessary to change fuses very often.

Under the above conditions, it has become necessary to either constantly replace the switches or to utilize separate clamping means to hold the contacts in place after the switch is closed. The first procedure, however, is not only troublesome but adds considerably to the expense of the manufacturing process, while the second procedure is not very feasible because it interferes with the eflicient operation of the work to have to attach or remove a clamp every time the switch is closed.

It is one object of the present invention to overcome the above difficulties by providing an electrical contact means wherein the operative engagement of the contacts is retained regardless of the amount of use thereof.

Another object of the present invention is to provide an electrical contact means of the aforesaid type wherein the pressure of the contacts may be adjusted as desired.

Another object of the present invention is to provide an electrical contact means of the aforesaid type wherein the contacts themselves need not be constructed of resilient or flexible material.

Another object of the present invention is to provide an electrical contact means of the aforesaid type wherein the contacts are held in parallel relationship to obtain maximum contact area.

Another object of the present invention is to provide an electrical contact means of the aforesaid type wherein the switch blade or other movable contact is easily insertable into and removable from engagement with the fixed contact means.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following description when read in conjunction with the accompanying drawings wherein:

FIG. 1 is a side elevational view of a double-throw electrical switch assembly embodying the present invention.

FIG. 2 is a cross-sectional view taken on line 22 of FIG. 1.

FIG. 3 is a cross-sectional view taken on line 33 of FIG. 1.

FIG. 4 is a perspective view of a cylindrical fuse holder embodying the present invention.

FIG. 5 is a perspective view of a fuse holder, embodying the present invention, for holding fiat fuse contacts.

Referring now in greater detail to the various figures of the drawing wherein similar reference characters refer 3,261,956 Patented July 19, 1966 to similar parts, there is shown a double-throw switch assembly, generally designated 10, which comprises a base 12, constructed of electrically insulating material and including a left-hand contact assembly, generally designated 14, a right-hand contact assembly, generally designated 16, and an intermediate switch-blade support assembly, generally designated 17.

Both the assemblies 14 and 16 are identical, so that the description of assembly 14 will suffice for a description of assembly 16. Accordingly, it is to be seen (as best shown in FIG. 2) that the assembly 14 comprises an upstanding electrically-conductive, flexible metal prong 18 having a lateral foot 20 connected to the base 12 by any desirable means such as a screw 22. The upper end of the prong 18 is provided with an upwardly and outwardly extending lip 24.

Adjacent to but spaced from the foot 20, there is connected to the prong 18 a second prong 26 constructed of similar flexible, electrically-conductive metal. The connection between the prongs is illustrated as being by means of a rivet 28, although any other desirable and feasible means may be used.

The prong 26 is also provided with an upwardly and outwardly extending lip 30 at its upper end and a loop 32 adjacent its lower end. Between the lip 30 and loop 32, the prong 26 is provided with a hole corresponding to a similar hole in the prong 18. A bolt 34 extends through these holes with its head against the outer surface of the prong 18 and the prong 26 being slidable thereon. The bolt 34 also extends through a hole in an arcuate bridge member 38, the ends of which abut the prong 26. This bridge member 38 may be constructed of any. desired material but it may sometimes be preferable to construct it of anodized aluminum or the like to prevent electrical conduction therethrough. Mounted on the bolt, adjacent the bridge member 38, is an electrically-insulating washer 40. A coil spring 42 is positioned around but spaced from the bolt between the washer 40 and a similar washer 44. A nut 46 on the bolt applies adjustable pressure on the washer 44 and spring 42. .The washers 40 and 44 prevent electrical conduction through the spring and, therefore, prevent loss of elasticity thereof.

A double-throw switch-blade 48 is pivoted on a bolt 50 extending between supports 52. This bolt 50 supports the same type of spring assembly as shown in FIG. 2, being provided with an arcuate bridge member 53 and a coil spring 54 positioned between insulating washers 55 and 56, the compression of the spring being adjustable by means of a nut 58. The blade 48 is pivot-ally movable between the fixed contact assemblies 14 and 16.

As shown in FIG. 2, the spring 42 normally biases the prong 26 against the prong 18. When the blade 48 is brought down, it forces its way between the prongs, spreading them against the pressure of the spring 42. The bolt 34 here acts as a limit stop for the blade 48.

In order to prevent the prong 26 from extending angularly from the prong 18, thereby preventing that complete contact with the corresponding surfaces of the switch-blade 43 which is most desirable, the loop 32 is provided to maintain parallelism between the two prongs and thereby maintain the desired full-surface contact. In this respect, it is preferable to vary the size of the loop in accordance with the thickness of the blade.

The tapered lips 24 and 30 guide the blade 48 into and out of position between the prongs, the blade being actuated by a lever 59.

The use of the adjustable spring 42 and bridge member 38 obviates the tendency of ordinary spring contacts, which depend only on their own resiliency or flexibility, to lose such resiliency or flexibility because of the conduct ofelectrical current therethrough, and because of trically-conductive metal.

the wear and tear of constant use. It also permits the use of lighter and less costly materials for the construction of the prongs since the flexibility and strength of the prongs is now primarily provided by the spring. Furthermore, the compression of the spring may be adjusted to compensate for wear or to adjust for different type blades.

As noted above, it is very desirable to maintain parallelism between the prongs. For this reason, it has heretofore, been necessary to construct the prongs of complicated configurations and to provide costly and complex attachment means. In the present construction, however,'the loop 32 permits the most simple type of construction :and assembly whereby it is merely necessary to provide the foot 20 on one prong and to connect this foot to the base member, the remaining connection being a simple connecting together of the two prongs by any simple means such as welding, riveting as at 28, bolting, etc.

Although the invention has been illustrated above as applied to a double-throw switch, it is, of course, equally applicable to a single-throw or any similar type switch. Furthermore, it is adaptable not only to electrical switches but to other type units. For example, it may be used in connection with fuse holders in the manner illustrated in FIGS. 4 and 5.

In FIG. 4 there is shown a fuse holder, generally designated 60, mounted on an electrically-insulating base 62. The fuse holder 60 includes a bottom portion 64 integral with two upstanding prongs 66 and 68, the prongs and bottom portion being constructed of a flexible, elec- A screw 70 connects the bottom portion 64 to the base 62, while the upper portions of the prongs from outwardly bowed jaws, as at 72 and 74 respectively, to enable them to clampingly embrace the cylindrical end 76 of a fuse, as shown in dotted outline.

The prongs 66 and 68 are held in releasably clamped position between the jaw 72 and 74 by a coil spring 78 mounted on a bolt 80 which extends through corresponding holes in the prongs 66 and 68. The head of the bolt 80 abuts the prong 68, similarly to the device of FIG. 2, while the opposite end of the bolt supports the spring 78 between an electrically-insulating washer 82 and a similar washer 84. A nut 86 holds the spring in adjustable compression against an arcuate bridge member 88 which, in turn, abuts at its ends against prong 66. The upper ends of the prongs are tapered outwardly, at 80 and 92, respectively, to form lips which permit easy insertion and removal of the fuse end. A loop 94 is provided in prong 66 for the same purpose as loop 32 in FIG. 2.

The operation of the device of FIG. 4 is similar to that of FIG. 2 and permit constant changing of fuses without loss of clamping capability of the holder.

In FIG. 5, there is shown a fuse holder similar to that of FIG. 4 but adapted to be used with flat fuse ends. In this embodiment, the fuse holder, generally designated 100, comprises a pair of flexible, electrically-conductive metal prongs 102 and 104 integral with a connecting portion 106. Each prong is provided with an outwardlytapering lip, as at 107 and 108, respectively, and prong 102 is also provided with a loop 110 similar in construction and function to loops 32 and 94.

A bolt 112 extends through the prongs 102 and 104, similarly to the device of FIGS. 2 and 4, and also similarly supports a spring 114 between insulating washers 116 and 118. A nut 120 provides adjustable compression for the spring. The spring applies its force against an arcuate bridge member 122 similar to members 38 and 88.

The device of FIG. operates in the same manner as that of FIG. 4 except that it is adapted to clamp a flat fuse end such as indicated in dotted outline at 123.

Although the fuse holders of FIGS. 3 and 4 have been illustrated as having intermediate portions, such as bottom portion 64 in FIG. 4 and connecting portion 106 in FIG. 5, these intermediate portions, which are primarily used for the purpose of maintaining the prongs parallel, may be eliminated and only a simple connection between the prongs, such as shown in FIG. 2, may be used. This is because the loops, such as shown at 32, 94 and 110, respectively, provide parallelism without such intermediate portions.

Obviously, many modifications of the present invention are possible in the light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

The invention claimed is:

1. An electrical contact means comprising a first electrically-conductive contact prong and a second electricallyconductive contact prong, said prongs being connected to each other to provide an electrical path therebetween, means for connecting said prongs to a support base, corresponding apentures in said prongs, a guide rod extending through said apertures, said rod being fixed to said first prong, said second prong being slidable on said rod, a bridge member slidably mounted on said rod and in abutment with that surface of said second prong which is remote from said first prong, a spring mounted on said rod in a position to apply resilient pressure on said bridge member, an adjusting nut threadedly engaged with said rod in a position to hold said spring under adjustable compression, said spring being electrically insulated from said bridge member and said nut, and a loop in said second prong, said loop being positioned between the connection of the two prongs to each other and the bridge member.

2. The electrical contact means of claim 1 wherein said pnongs are connected to each other at an apex.

3. The electrical contact means of claim 1 wherein each prong is provided with an outwardly-extending angular lip at that end thereof which is opposite the connection therebetween, the lip of one prong extending in an opposite angular direction to the lip of the other prong to provide a cam-like entrance for a contact movable between the two prongs.

4. An electrical switch means comprising an electrically-insulated base, at least one fixed electrical contact assembly mounted on said base, and a movable contact mounted on said base for movement into and out of electrical engagement with said fixed contact assembly, said fixed contact assembly comprising a first electricallyconductive contact prong and a second electrically-conductive contact prong, said prongs being connected to each other to provide an electrical path therebetween, means for connecting said prongs to a support base, corresponding apertures in said prongs, a guide rod extending through said apertures, said rod being fixed to said first prong, said second prong being slidable on said rod, a bridge member slidably mounted on said rod and in abutment with that surface of said second prong which is remote from said first prong, a spring mounted on said rod in a position to apply resilient pressure on said bridge member, an adjusting nut threadedly engaged with said rod in a position to hold said spring under adjustable compression, said spring being electrically insulated from said bridge member and said nut, and a loop in said second prong, said loop being positioned between the connection of the tWo prongs to each other and the bridge member, said movable contact being selectively movable into and out of a circuit-closing position between the prongs of the fixed contact assembly, said movable con tact being constructed and arranged to spread said prongs away from each other against the bias of said spring when said movable contact is in said circuit-closing position, and said spring being constructed and arranged to hold said prongs in firm resilient engagement with said movable contact while said movable contact is in said circuit-closing position.

5. The electrical switch means of claim 4 wherein the prongs of said fixed contact assembly are connected to each other at an apex.

6. The electrical switch means of claim 4 wherein each prong is provided with an outwardly-extending angular lip, the lip of one prorug extending in an opposite direction from the lip of the other prong, the lip on each prong being at that end of the prong which is opposite the connection between the prongs.

7. An electrical fuse holder comprising a first electrically-conductive contact prong and a second electricallyconductive contact prong, said prongs being connected to each other to pnovide an electrical path therebetwee-n, means for connecting said prongs to a support base, corresponding apertures in said prongs, a guide rod extending through said apertures, said rod being fixed to said first prong, said second :prong being slidable on said rod, a bridge member slidably mounted on said rod and in abutment with that surface of said second prong which is remote from said first prong, a spring mounted on said rod in a position to apply resilient pressure on said bridge member, an adjusting nut threadedly engaged with said rod in a position to hold said spring under adjustable compression, said spring being electrically insulated from said bridge member and said not, and a loop in said second prong, said loop being positioned between the connection of the two prongs to each other and the bridge member, said prongs forming flexibly-biased jaws for clamping an end of a fuse.

8. The electrical tfllSB holder of claim 7 wherein the jaws are arcuate to embrace cylindrical fuse contacts.

9. The electrical fuse holder of claim 7 wherein the jaws are fiat to embrace fiat fuse contacts.

References Cited by the Examiner UNITED STATES PATENTS 2,632,829 3/1953 Hobbs et a1. 200 -162 ROBERT S. MACON, Acting Primary Examiner.

H. HOHAUSER, Assistant Examiner. 

1. AN ELECTRICAL CONTACT MEANS COMPRISING A FIRST ELECTRICALLY-CONDUCTIVE CONTACT PRONG AND A SECOND ELECTRICALLYCONDUCTIVE CONTACT PRONG, SAID PRONGS BEING CONNECTED TO EACH OTHER TO PROVIDE AN ELECTRICAL PATH THEREBETWEEN, MEANS FOR CONNECTING SAID PRONGS TO A SUPPORT BASE, CORRESPONDING APERTURES IN SAID PRONGS, A GUIDE ROD EXTENDING THROUGH SAID APERTURES, SAID ROD BEING FIXED TO SAID FIRST PRONG, SAID SECOND PRONG BEING SLIDABLE ON SAID ROD, A BRIDGE MEMBER SLIDABLY MOUNTED ON SAID ROD AND IN ABUTMENT WITH THAT SURFACE OF SAID SECOND PRONG WHICH IS REMOTE FROM SAID FIRST PRONG, A SPRING MOUNTED ON SAID ROD IN A POSITION TO APPLY RESILIENT PRESSURE ON SAID BRIDGE MEMBER, AN ADJUSTING NUT THREADEDLY ENGAGED WITH SAID ROD IN A POSITION TO HOLD SAID SPRING UNDER ADJUSTABLE COMPRESSION, SAID SPRING BEING ELECTRICALLY INSULATED FROM SAID BRIDGE MEMBER AND SAID NUT, AND A LOOP IN SAID SECOND PRONG, SAID LOOP BEING POSITIONED BETWEEN THE CONNECTION OF THE TWO PRONGS TO EACH OTHER AND THE BRIDGE MEMBER. 